Lessons learned about adult kidney stem cells from the malpighian tubules of Drosophila.

All multicellular organisms have a specialized organ to concentrate and excrete wastes from the body. The kidneys in vertebrates and the malpighian tubules in Drosophila accomplish these functions. Mammals and Drosophila share some similar features during renal tubular development. Vertebrate kidneys are derived through the mutual induction of the ureteric bud and metanephric mesoderm, whereas the malpighian tubules of Drosophila develop from the hindgut primordium and visceral mesoderm. The vertebrate kidney also has the capacity to recover and regenerate following episodes of acute injury. Previous studies suggest that stem cells and progenitor cells may be involved in the repair and regeneration of injured renal tissue. However, studies differ as to the source of the regenerating renal cells. Recently, multipotent stem cells in Drosophila malpighian tubules were identified, and it was demonstrated that several differentiated cells in the malpighian tubules arise from these stem cells. In this article, the current understanding of kidney development and stem cell fate in mammal and Drosophila is compared. Furthermore, the potential application of the adult renal stem cells in kidney repair and the treatment of kidney cancers are discussed.